The present invention relates to semiconductor structure, and in particular to an interconnect structure for semiconductor devices with hollow honeycomb-like dielectric integrated with conductor.
Reduction of integrated circuit feature size has resulted in levels of electrically conductive interconnects being placed closer together vertically, as well as reduction of the horizontal spacing between the electrically conductive interconnects, such as metal lines. As a result, capacitance has increased between such conductive portions, resulting in RC (resistance×conductance) delay time and crosstalk-effect. One proposed approach to this problem is to replace the conventional silicon oxide (SiO2) dielectric material, having a dielectric constant (k) of about 4.0, with another insulation material having a lower dielectric constant to thereby lower capacitance.
Unfortunately, low-k dielectric materials have various problems that make integration into existing integrated circuit structures and processes difficult. Compared to conventional silicon dioxide (SiO2), most low-k materials, due to the inherent structures thereof, especially for porous ultra low-k dielectric, typically present characteristics such as lower mechanical strength and unstable stress levels. These issues are critical as processing and packaging due to weak mechanical strength. Thus, the replacement of conventional silicon dioxide (SiO2) with ultra low-k dielectric material in integrated circuit (IC) processes or structures generates structural damage when subjected to external stress during processing, thereby affecting reliability of a formed semiconductor device.
In the field of aerospace, the optimization of structure strength and weight of airplane is to use honeycomb-like structure based on FEM (Finite Element Method) calculation after WW2 and constituted by Al, Ti, alloys thereof and even composite-based material. It is pretty straightforward thinking to apply and integrate honeycomb-like dielectric structure into the most advanced semiconductor device for best electrical as well as mechanical performance.
Thus, an interconnect structure incorporating low-k dielectric material with reinforced mechanical strength is desired.